With the recent increase in concern about environmental issues, the demand on automobiles for better fuel economy is increasing. Better fuel economy is also being required of rubber compositions used for automotive tires. For example, rubber compositions containing a conjugated diene polymer (e.g. polybutadiene, butadiene-styrene copolymer) and a filler (e.g. carbon black, silica) are used for automotive tires.
Patent Literature 1 proposes a method for improving fuel economy; this method uses a diene rubber (modified rubber) that is modified by an organosilicon compound containing an amino group and an alkoxy group. Although this method enables to improve fuel economy, it unfortunately does not achieve sufficient grip performance on wet road surfaces or in cold regions. Thus, the method needs improvement for ensuring safety. Moreover, automotive tires need to achieve stable wet-grip performance all year round to ensure safety. Thus, improvements are required in wet-grip performance and the temperature dependence of wet-grip performance, as well as in fuel economy.